Preparation of halides



July 16, 1946. E VLKGORIN PREPARATION OF HALIDES T Filed March 19, 1943 2 Sheets-Sheet 1 RAF/4 CTO/P REA C 7 OR MOIST/ 6r FIG.

Everett 60m? lNVEN TOR A r TORNEV Ernest B.

Patented July 16, 1946 rnnraaa'rron or HALIDES Everett Gorin, Dallas, Tex., assignor, by memo as,-

to Socony-Vacuum Oil Company,

a corporation of Appl icatlon March 19, 1943, Serial No. 479,808

(c1. zs-se) signments, Incorporated, New York, N. Y., New York '12 Claims. 1 This invention relates to the recovery of aluminum halide catalysts from aluminum halide-hydrocarbon complexes formed when aluminum halides are used as catalysts for the catalytic conversion of hydrocarbons. More particularly this invention is concerned with the recovery of the halogen content of aluminum halide tarry complexes.

It has been proposed to recover-the halogen content of such tars by either-hydrolyzing the tar or by burning the tar in the presence of air. Both of these methods produce the halogen acid in admixture withwater vapor.. This moist halo gen acid isnot suitable for the production and regeneration of the aluminum halide.

The problem 01 producing the anhydrous halogen acid from the moist acid is not an easy one because the ordinary regenerable desiccants such as silica gel, bauxite, activated alumina, calcium halides, etc., absorb considerable quantities of the halogen acid along with the water vapor. Anhydrous hydrochloric acid may be produced from the moist acid containing more than percent hydrogenchloride by low temperature tractionation, but this is a difllcult and expensive operation and only incomplete recovery of the hydrogen chloride content is obtained Instead oi. converting the moist halogen acid into an anhy drous halogen acid, and ma aluminum halide from the anhydrous acid, I propose to convert the halogen content of the moist halogen acid into a reactive metal halide which has a very small amnity for water vapor. "I'hereactive halide is then reacted with metallic aluminum, aluminum carbide or an alumina-coke mixture to reform the aluminum halide catalyst.

My invention is primarily concerned with the development of a process for the recovery and reutilization of the halogen acids produced by the hydrolysis of spent. catalyst residues or produced by the combustion of the spent catalyst residues in air. I am particularly concerned withthe aluminum halide catalyst residues produced when thesecompounds are'used as catalysts for the catalytic conversion of hydrocarbons. The use of aluminum chloride for the catalytic conversion of hydrocarbons is well known. In the reaction complex aluminum chloride-hydrocarbon compounds are formed which are of a tarry charac .ter.

Many processes have been-proposed tor the recovery of the aluminum chloridevalues. from these tars. Prominent among the methods proposed is that of hydrolyzing the'tar. A typical process for such hydrolysis is that disclosed by Phillips in U. S. Patent 1,760,962,

. 2 granted June 3, 1930.' Aluminum bromide when used as a catalyst for the conversion of hydrocarbons also reacts with thehydrocarbons to form a complex tar as disclosed in copending application. Serial No. 448.886, nledJune 29, 1942, by Manuel H. 6min and W111 swerdlofi. The aluminum bromide values in these tarry residues may also be separated from the hydrocarbons by hydrolysis of the tar. This hydrolysis is generally carried out by subjecting the tar to the action of steam. As aresult of the hydrolysis of either an aluminum chloride or aluminum bromide tar there is produced the corresponding halogen acid mixed with large amounts of water vapor. The halogen acids in a moist condition cannot be usedfor regeneration of the aluminum halide-catalyst without the prior removal or the water.

It is an object o! my invention to prepare a substantialLv anhydrous halogen compound from a moist halogen acid produced by the hydrolysis or combustion of an aluminum halide tar residue which is suitable for use in regenerating the aluminum halide catalyst.

Another object of my invention is the regeneration of an aluminum halide catalyst utilizing the halogen content or an aluminum halide catalyst residue by producing a moist halogen acid from the tar residue and converting this into an anhydrous reactive halide compound.

Other and further objects or my invention will be apparent from the description thereof and from the appended claims.

According to the processor my invention the halogen content of the moist halogen acid produced by the hydrolysis of spent catalyst residues is recovered in a substantially anhydrous form by converting the halogen acid intoa reactive halide which has a very small afllnity for water vapor. According to my processthe moist halogen acid is reacted with ar heavy metal selected from the group consisting of lead, zinc, tin. silver, copper and mercury. Preferably the metal is reacted with the moist halogen acid while in a molten or vapcrous condition. Metals which have a high melting point such as silver and copper may be alloyed with metals such as zinc, lead or mercury to form a lower melting alloy, and thus avoid the necessity for the use of extremely high temperatures in the process with consequent increase in operating difliculties.

The reaction is preferably carried out in the does not always go to completion, especially where the metal is silver or mercury. Likewise, even where the reaction would go to completion, the addition of oxygen usually makes the reaction proceed more rapidly possibly because of the removal of one of the products of the reaction. In the presence of oxygen the reaction may be expressed as Where oxygen or air is used, however, the quantity of oxygen used must not be in excess of that theoretically required to convert all of the hydrogen liberated by the reaction of the halogen acid with the metal to water. Were excess oxygen to be used part of the metal would be converted to the oxide. Preferably slightly less air or oxygen is used than is theoretically necessary to convert all of the liberated hydrogen to water. It is also preferable to introduce oxygen throughout the reaction --zone to minimize the occurrence of zones in which there is excess oxygen wherein the metal oxides would be formed. My invention may be better understood by reference to the drawings and the description of the specific preferred mode of operation thereof.

Referring to Figure 1; a hydrogen bromidesteam mixture obtained by the hydrolysis of an aluminum bromide tar is fed into the reactor I, 2, provided with a suitable control valve 3. Air is introduced into the reactor through the lines 4, 5, and 6, connected to a source of compressed air (not shown) from line I. Control valves 8, 9, and 5, and 6, respectively, so that the distribution oi the air in the reaction zone may be controlled. Molten lead is fed into the top of the reactor through the line II. The reactor l is packed with an inert material I2, such as refractory Raschig rings or Carborundum chips over which the molten lead flows in its descent through the reactor. This serves to provide good contact between the descending molten lead and the ascending hysteam, and the oxygen. Suitwithin a temperature range of from 375 C. to 600 C. The reaction is highly exothermic, and, therefore, with a properly constructed reactor it is possible'to maintain the temperature within the desired range with little or no external heating. The reaction is preferably carried at a temperature as little as possible above 375 C. to .minimize difilculties arising from volatilization of the halide.

As a result of the reaction between the hydrogen bromide and the molten lead flowing downwardly through the reactor, part of the lead is converted to lead bromide, which is molten at the temperature in the reactor. This molten lead bromide and the unreacted lead flow out of the bottom of the reactor through line I3, into settling tank 14:. Water vapor, produced as a result of the reaction between the lead and the hydrogen bromide in the presence of oxygen, and from the initial mixture, together with the nitrogen'from the air flow out from the top of the reactor through line I5. In the settling tank I 4, the lead and the lead bromide separate into two layers because of the difl'erence in their specific gravities. The lead which settles to the bottom is drawn ofi through line I 6 and returned to line II through line I! by means of the pump I8. Suitable means (not shown) are provided to maintain the lead in the settling tank I4 and in the lines I6, I1, and II in the molten condiuniformly I 0, are provided in lines 4,

'of the lead bromide. .aluminum will react tion. The lead bromide is drawn ofl from the settling tank through the line I9 and is fed through line 20, into a second reactor 2|. A pump 22 is provided in line 20 to feed the molten lead bromide. Reactor 2| is packed with metallic aluminum 23 in the form of granules, chips, or turnings. The molten lead bromide flows down through the metallic aluminum contained in the reactor 2|, which is maintained at a temperature slightly above the melting point At this temperature the vigorously with the lead bromide to reform the aluminum bromide cat- Molten lead regenerated by this reaction flows from the bottom of the reactor 2|, through line 24, and is returned to the settling tank I4, for recycling in reactor I. Aluminum bromide which is volatile at the temperature in reactor 2| is vaporized and driven out from the top thereof through line 25, condensed in condenser 26, and the molten aluminum bromide sent through line 21, either to product storage or reused directly in a hydrocarbon conversion process. Metallic aluminum is supplied to reactor 2|, from hopper 28, through the gas sealed rotary valve 29, opcrated'by'a motor (not shown).

Referring to Figure 2, the operationof the reactor IOI and the settling tank II 4 is the same as described previously in connection with the description of the process illustrated by Figure l. InFigure 2, however, the aluminum halide is regenerated by the use of aluminum carbide or an alumina-coke mixture instead of metallic aluminum. When aluminum is in the form oi! the carbide considerably higher temperatures are desirable in order to bring about the reaction, and it is preferable to add the lead bromide in the form of a vapor. The temperature of the reactor IN is maintained above 600 C., preferably at 700 to 1000 C. In order to flows from the top of the vaporizer I30, through line I33, into the bottom of reactor I2I. Preterably a trap I34 is provided in line IIB to prevent lead bromide vapor from flowing back through line II9 into the settling tank H4. The lead bromide vapor in ascending through the reactor I2 I reacts with the aluminum carbide to liberate the metallic lead and to form aluminum bromide. The aluminum bromide passes out from the top of the reactor I2I, through line I25, is condensed in line I26, and recovered from line I21, as described in connection with the description of Figure l. The molten lead liberated by the reaction is returned to the settling tank II4, through line I24, as previously described in connection with the description of Figure 1.

The methods of carrying out my process as described mixture or aluminum carbide. or silver are used be formed from the action of the copper or silver halide on aluminum the procedure described below is preferred to avoid the difliculty of reforming the alloy from the halide mixture at a temperature below the melting point of aluminum.

With copper or silver, the packing would be eliminated from the reactors shown inFigures l and 2, except for an upper packed section. The lower part of the first reactor would be charged with copper or silver powder. The moist halogen acid entering the reactor would react with the metallic powder, and. under the reaction conditions, form the molten metallic halide. The halide would be passed to a second reactor having the same general arrangement as the first, but filled with metallic aluminum powder or turnings. The reaction between the metallic halide and th aluminum would form aluminum halide vapor as described previously, and liberate the copper or silver as a powder. Part of this powder would tend to pass out of the second reactor with the heavy aluminum halide vapor, but most of this would be removed by the packing. Obviously, a suitable arrangement of baffie plates in the top of the reactor could be employed instead of the packing. The reaction would be continued until all of the aluminum were halogenated to aluminum halide. The second reactor would then contain metallic silver or copper in powder form, and would then be treated with the moist halogen acid air mixture to reform the metallic halide. ,Reactor i, would have had most or all of its metal powder charge halogenated, and would then be charged with metallic aluminum. The metallic halide being formed in the second reactor would be flowed into the first reactor at a point below the packed section wherein aluminum halide would be formed in the same manner as described above. The operation would be cyclic in character, with moist acid and metallic aluminum charged alternately to each reactor. In such a process the 'reaction should be run until all of-the aluminum has been driven oflf as aluminum halide before the cycle is reversed by feeding the moist halogen acid into the reactor. Excess copper or silver mixed with the aluminum in the aluminum halide formation step would do no harm, and would be advisable so that there would be suflicient copper or silver for the metallic halide formation step. A small amount of copper or silver as make-up may be charged along with the aluminum, since some of these metals would be lost from the reaction zone into'the packing. Periodically the packing may be removed from the upper sections of the reactors and the copper or silver recovered therefrom by treatment with the moist halogen acid.

Inasmuch as mercuric halides normally sublime, at atmospheric pressure, the system described; above in connection with the discussion of Figures l and 2 would have to be maintained under pressure where this material was used in the process. Instead of operating the system under pressure,it might be preferable to allow the mercuric halide vapor to pass overhead along with the water vapor and inert gases from the first reactor. Since the mercuric halide vapors will condense at temperatures considerably above the other gases present in the mixture, the mercuric halide would be condensed directly to a solid, and separated from the water and inert gases. The mercuric halide would then be revaporized, and passed through the metallic aluminum in the manner shown in Figure 2. Preferably two condensers would be used, one of which would be serving as a revaporizer, and the other as a condenser, in cyclic operation so that the process would be continuous.

Some of the metals, particularly tin, and to a lesser extent copper, lead and zinc, will be partly oxidized at the high temperatureinvolved even though the oxidizing gas contains an excess of HBr. Localized overheating and zones of excess oxygen are substantially-impossible to prevent in a commercial apparatus. It is therefore desirable that the metal-metallic halide mixture be scrubbed with the incoming moist acid prior to its discharge from the reaction zone. At the reaction temperature any oxidized metal will be halogenated by the acid and the halide of the metal formed. For this reason the principle of eountercurrent flow of the metal and the moist halogen acid is especially advantageous with the oxidizing gases introduced at an intermediate zone. This is particularly true in the case of tin because in the presence of an oxidizing gas the stannous bromide will readily be oxidized to stannic oxybromide. By contacting this compound with halogen acid in the presence of metallic tin the stannic oxybromide will be reduced according to the equation the advantage that there is always sufficient metal to react with the halogen content of the moist halogen acid being treated. It also insures the formation of the lower valence halide in those cases in which the metallic halide might have either of two valences. This is particularly important in the case of such metals as tin and copper. In the case of, tin, the stannic chloride if it were formed would be hygroscopic. In the case of copper the cupric chloride sublimes at very high temperature and this material would be extremely diflicult to handle.

I have referred to the use of an alumina-coke mixture for reacting with the reactive metallic halide to reform the aluminum halide catalyst. This reaction, like that withaluminum carbide, requires the use of high temperatures; in the neighborhood of 1000 C., to eflect the desired reaction.- I The alumina-coke mixture may be derived from the residue of the tar catalyst after the halogen has been recovered by hydrolysis by heating to drive off first the water, then the hydrocarbons, and finally given an oxidizing roast to form an alumina-coke residue. Where the alumina-coke residue is utilized as the source of the aluminum for the regeneration of the aluminum halide catalyst obviously all the values ofthe original catalyst are recovered and regenerated in the original form. Whether it is more economical to recover the aluminum value in the catalyst-residue or merely to recover the halogen value and utilize scrap aluminum to regenerate the catalyst is a matter to be determined by the relative quantities available, the cost of building and operating the equipment at the higher temperature level with the alumina-coke residue and the cost and availability of scrap aluminum.

The following specific example illustrates the process of my invention:

Example The tarry residue settling out of a normal par- 7 afiln isomerization reaction, in which the reaction,

carried out in the liquid phase, was catalyzed by packing. A stream of molten lead at a temperature of 500 C. was flowed downwardly through the tower countercurrent to the ascending gas stream. The eflluent from the bottom of the tower was allowed to separate into two layers, and the upper or lead bromide layer weighed 598 grams. This quantity of plumbous bromide con. tains 259 grams of bromineindicating that 98.6 percent of the hydrogen bromide was converted to molten anhydrous lead bromide.

The molten lead bromide was then contacted with granular metallic aluminum at a tempera ture of 450 C. A vigorous reaction set in immediately and the aluminum bromide formed distilled out of the reactor. The aluminum bromide vapor was condensed, and 282 grams of aluminum bromide recovered. This indicated that 252.5 grams of bromine or 97.5 percent of the bromine in the lead bromide was recovered as aluminum bromide. The overall recovery of aluminum bromide for the process was 282 grams out of an original 308 grams or 91.6 percent. 30 grams of aluminum were required for the regeneration of the aluminum bromide.

The reaction between th moist halogen acid and the metal is preferably effected at a temperature not greater than about 700 C. At higher temperatures the metallic halide becomes increasingly reactive with the water vapor. The volatility of the metallic halide also becomes too high at higher temperatures. The reaction may be carried out within the temperature range of from 300 to 700 C., with the temperature preferably maintained between about 375 C. and about 600 C. The temperature at which the halide'is reacted with the aluminum is not particularly important, but for proper operation of the process a temperature between the melting point of the halide and the melting point oi the aluminum is used. Preferably the temperature is maintained as low as possible consistent with the maintenance of the halide in the molten condition. with the high melting halides, as mentioned above, the reaction may be carried out between molten aluminum and the solid halide.

In the case of the reaction between the metal halide and aluminum carbide higher temperatures, in the neighborhood of 700 C. or higher are required. Where an alumina-coke mixture is used, still higher temperatures, in the neighborhood of 1000 C. are necessary.

The foregoing description of my invention is illustrative of the preferred embodiments thereof, and my invention is not to be construed as limited except as indicated in the appended claims.

I claim:

1. Th process for the recovery of the chlorine content of moist hydrogen chloride produced from an aluminum plex formed when aluminum chloride is used as a catalyst for a hydrocarbon conversion process and the production of aluminum chloride therefrom which comprises passing the mixture of hydrogen chloride and water at a temperature between 300 C. and 700 C. in contact with a metal chloride-hydrocarbon com selected from the group consisting of lead, zinc,

tin, silver, copper and mercury, whereby the corresponding metal chloride is formed by the action of the hydrochloric acid on the metal, separating the water from the metal chloride, reacting the metal chloride at a temperature above 300 C. with a member of the group consisting of metallic aluminum, aluminum carbide, and an alumina-coke mixture, collecting the evolved alu- -minum halide vapor and condensing and recovering the aluminum chloride.

2. The process for the recovery of the bromine content of moist hydrogen bromide produced from an aluminum bromide-hydrocarbon complex formed when aluminum bromide is used as a catalyst for a hydrocarbon conversion process and the production of aluminum bromide therefrom which comprises passing the mixture of hydrogen bromide and water at a temperature between 300 C. and 700 C. in contact with a metal selected from the group consisting of lead, zinc, tin, silver, copper and mercury, whereby the corresponding fnetal bromide is formed by the action of the hydrobromic acid on the metal, separating the water from the metal bromide, reacting the metal bromide at a temperature above 300 C. with a member of the group consisting of aluminum, aluminum carbide, and an alumina-coke mixture, collecting the evolved aluminum halide vapor and condensing and recovering the aluminum bromide.

3. The process for the recovery of the halogen content of a moist halogen acid selected from the group consisting of moist hydrochloric acid and moist hydrobromic acid produced from an aluminum halide-hydrocarbon complex formed when the corresponding aluminum halide is used as a catalyst for a hydrocarbon conversion process and the production of aluminum halide therefrom which comprises passing the mixture of halogen acid and water in the vapor phase at a temperature between 300 C. and 700 C. in contact with a metal selected from the group consisting of lead, zinc, tin, silver, copper and mercury, whereby the corresponding metal halide is formed by the action of the halogen acid on the metal, separating the water from the metal halide, reacting the metal halide at a temperature above 300 C. with a member oi the group, consisting of metallic aluminum, aluminum carbide, and an alumina-coke mixture, collecting the evolved aluminum halide vapor and condensing and recovering the aluminum halide.

4. The process for the recovery of the halogen content of a moist halogen acid selected from the group consisting of moist hydrochloric acid and moist hydrobromic acid produced from an aluminum halide-hydrocarbon complex formed w en the corresponding aluminum halide is used as a 5. The process for the recovery of the halogen content of a moist halogen acid selected from the moist hydrochloric acid and group consisting of moist hydrobromic acid produced from an aluminum halide-hydrocarbon complex formed when the corresponding aluminum halide is used as a catalyst for a hydrocarbon conversion process and the production of aluminum halide therefrom which comprises passing the mixture or the halogen acid and water in the vapor phase into a packed reactor, flowing molten lead through the reactor countercurrent to the stream of moist halogen acid vapors, admitting oxygen into the reactor at a plurality oi points intermediate the points 0! entry of the molten lead and the moist halogen acid vapors, regulating the quantity of oxygen added so that not more than one mole of oxygen is added per four moles of halogen acid, whereby the corresponding lead halide is formed by the action of the halogen acid on the molten lead, separating the water from the lead halide, reacting the lead halide at a temperature above 300" C. with a member of the group consisting oi metallic aluminum, aluminum carbide, and an alumina-coke mixture, collecting the evolved aluminum halide vapor and condensing and recovering the aluminum halide.

6. The process for the recovery of the halogen content of a. moist halogen acid selected from the group consisting of moist hydrochloric acid and moist hydrobromic acid produced from an aluminum halide-hydrocarbon complex formed when the corresponding aluminum halide is used as a catalyst for a hydrocarbon conversion process and the production of aluminum halide therefrom which comprises passing the mixture of the halogen acid and water in the vapor phase into a packed reactor containing metallic copper, admitting oxygen into the reactor, regulating the quantity of oxygen added so that not more than one mole of oxygen is added per four moles of halogen acid, whereby the corresponding copper halide is formed by the action of the halogen acid on the metallic copper, separating the water from the copper halide, reacting the copper halide at a temperature above 300 C. with a member of the group consisting of metallic aluminum, aluminum carbide, and an alumina-coke mixture, collecting the evolved aluminum halide vapor and condensing and recovering the aluminum halide.

7. The process of claim 4 in which the halogen recovered is chlorine.

8. The process of claim 4 in which the halogen recovered is bromine.

9. The process for the recovery of the halogen content or a moist halogen acid selected from the group consisting of moist hydrochloric acid and moist hydrobromic acid produced from an aluminum halide-hydrocarbon complex formed when the corresponding aluminum halide is used as a catalyst for a hydrocarbon conversion process and the production or aluminum halide therefrom which comprises passing the mixture or the halogen acid and water in the vapor phase into a packed reactor. flowing molten lead through the reactor countercurrent to the stream of moist halogen acid vapors, admitting oxygen into the reactor at a plurality of points intermediate the points of entry 01' the molten lead and the moist halogen acid vapors, regulating the quantity of oxygen added so that not more than one mole of oxygen is added per four moles of halogen acid, whereby the corresponding lead halide is formed by the action or the halogen acid on the molten lead, separating" the water from .the lead halide, reacting the lead halide at a temperature above 300 C. with metallic aluminum, collecting the evolved aluminum halide vapor and condensing and recoveringthe aluminum halide.

10. The process of claim 9 in which the halogen recovered is bromine.

11. The process for the recovery of the bromine content of moist hydrobromic acid which comprises passing the moist hydrobromic acid into the bottom portion of a packed reactor, introduclng a regulated quantity of oxygen into the reactor such that the quantity of oxygen added is not more than one mole per four moles of hydrogen bromide, flowing molten lead downwardly through the reactor over the packing material while maintaining the temperature within the reactor between 300 C. and 700 0., separating oil water vapor from the top 01' the reactor and withdrawing a mixture of molten lead and lead bromide from the bottom of the reactor, returning the unreacted lead to the reactor, transferring the molten lead bromide to a second reactor containing solid metallic aluminum, main 7 tainin the second reactor at a temperature above 300 C., collecting and condensing aluminum halide vapor evolved from the second reactor. withdrawing the molten lead formed in the second reactor and recycling the lead to the first reactor.

1 The process for the production of an aluminum halide catalyst from a member of the group consisting of metallic aluminum, aluminum carbide, and an alumina-coke mixture, and a moist halogen acid selected from the group consisting of moist hydrochloric acid and moist hydrobromic acid which comprises passing themixture of halogen acid and water in the vapor phase at a temperature between 300 C. and 700 C. in contact with a metal selected from the group consisting of lead, zinc, tin, silver, copper and mercury, whereby the corresponding metal halide is formed by the action of the halogen acid on the metal, separating the water from the metal halide, reacting the metal halide at a temperature above 300 C. with a member of the group consisting of metallic aluminum, aluminum carbide, and an alumina-coke mixture, collecting the evolved aluminum halide vapor, and condensing and recovering the aluminum halide catalyst.

EVERETT GORIN. 

